A raw image file contains the data straight from the sensor, but ALSO it includes a lot of information about your camera settings at the time the picture was taken.

You can load up the raw image into Canon DPP or some other software to produce JPEG images. In the case of the better software, it will generally read the camera settings information and start you out with the same image that the camera would have saved as JPEG. This is just a starting position-- you can then tweak the image by trying out different settings. "Oh, what if I tried with a different white balance? Or a different sharpness? Or one of the camera styles like Faithful or Sepia?"

A raw image cannot change what your ISO, Tv, Av or focus was at the time you took the picture. (You can emulate pushing ISO by pushing image data, but you can't actually change the gain applied to the sensor.) Everything else is up to how you play with the settings in the raw image loading software on your computer.